ULS, which runs on Windows NT 3.51 with Service Pack 4 or on NT 4.0, is a directory service that lets you locate other network users for NetMeeting conferences. The program loads and runs under Microsoft's IIS as an Internet Server API (ISAPI) DLL file.

ULS doesn't come with NetMeeting, so to install and run ULS, you need to download it from Microsoft's Web site and copy the DLL into IIS's root Web directory. You then use File Manager or Explorer to grant the DLL file appropriate execute rights. The installed ULS is only about 31KB.

When you configure NetMeeting, you enter several pieces of information, including your name, your email address, your location, a brief description of yourself, your preferred ULS server, and whether you want your information made available to everyone on a ULS server. Users who want to participate in the same conference can be on different ULS servers; you just need to know which servers the other participants are on before you can initiate the conference.

If you want to share your information, NetMeeting tries to connect to your specified ULS server. On a successful connection, NetMeeting transmits your personal information to ULS for temporary storage and retrieval. This storage is temporary because ULS stores the information only while you have NetMeeting running. After you close the software, ULS removes your information. So if you close NetMeeting and a conference member is trying to find you, your ULS information won't show up.

ULS offers two ways to browse its directory information. First, you can click Refresh on NetMeeting's toolbar to download the entire user listing from the ULS server you select from the Directory pulldown menu. NetMeeting then displays this list in the lower list box, as you see in Screen 1 of the main article. Second, you can use a standard Web browser, as you see in Screen A, to connect to someone directly from a Web page. Because the ULS server is a DLL, you can call it directly by entering a URL such as uls.microsoft.com/ulserver.dll?action=directory into a Web browser.